Cases on gas turbine engines may be assembled and fixed using interference snaps on adjacent flanges. The disassembly of a snap fit may involve jack screws, which thread into one member and push against the adjoined member. Thus, the adjacent flanges may be separated using a jack screw. A jacking insert may include a threaded cylinder attached to a small flange that takes the jacking load. The flange is sandwiched between the flanges of the components snapped together (e.g., adjacent segments of an engine case). The jacking feature may sit recessed in one of the two flanges to be snap-fit together. The recess is typically either circular or rectangular.
A circular jacking feature is not fixed against rotation within the recess and may spin when the jacking screws are in use. In many instances a second wrenching feature may be used to prevent a circular jacking feature from spinning. If the spot face is rectangular, the slot is usually cut through the flange so that it is easy to manufacture. However, in this manner, the thickness of the case flange that is full hoop is reduced and compromises the structural integrity of the case flange.